My Dart has a 225 from a '74 Charger. I'm running my points distributor right now, but the Charger came with an electronic ignition distributor. I've been thinking of buying an LX101 box and running it, but do I need to change my Dart's ballast resistor? I see on Rock Auto that some of them for '74 Chargers have four connection points, and some have two.
Dumb ballast resistor question
- Thread starter Aaron65
- Start date
-
So far as I know, none of the aftermarket replacement boxes require a 4 pin resistor. This was a running production change by Mopar
The older "5 pin" ECU requires a 4 pin resistor
The newer "4 pin" ECU can use a 2 pin, if you have a 4, it just isn't doing anything on the "second half."
You can NOT identify a 4 / 5 pin ECU by looking. Many boxes are electrically 4 pin, but have 5 physical pins. Only way to tell is "ohm out" the 5th pin and see if it goes anywhere
Unless you go "junkyarding" I doubt you'll buy a new box that is 5 pin
Diagrams: (from MyMopar)
Older 5 pin box, 4 pin resistor The "U" cutout in the ceramac ballast orients the resistor, which is different resistance on each side
Newer 4 pin box, 2 pin resistor. Notice that they essentially eliminated the "left half."
You might also keep this in the back of your head..........If your Mopar ECU breaks on the road, and you have your old points distributor, all you need to do is exchange distributors, unhook the coil NEG wire, and hook the distributor up to the coil NEG terminal. Yank the plug off the ECU. 5 minutes, and off you go
The older "5 pin" ECU requires a 4 pin resistor
The newer "4 pin" ECU can use a 2 pin, if you have a 4, it just isn't doing anything on the "second half."
You can NOT identify a 4 / 5 pin ECU by looking. Many boxes are electrically 4 pin, but have 5 physical pins. Only way to tell is "ohm out" the 5th pin and see if it goes anywhere
Unless you go "junkyarding" I doubt you'll buy a new box that is 5 pin
Diagrams: (from MyMopar)
Older 5 pin box, 4 pin resistor The "U" cutout in the ceramac ballast orients the resistor, which is different resistance on each side
Newer 4 pin box, 2 pin resistor. Notice that they essentially eliminated the "left half."
You might also keep this in the back of your head..........If your Mopar ECU breaks on the road, and you have your old points distributor, all you need to do is exchange distributors, unhook the coil NEG wire, and hook the distributor up to the coil NEG terminal. Yank the plug off the ECU. 5 minutes, and off you go
Thank you very much for the diagram and explanation. I'd just be buying a replacement module, so it'd likely be the 4-pin type, and the Dart now has a 2-pin resistor. Now that I think about it, I believe I'm missing the wiring harness from the distributor to the module. Does anyone reproduce those, or is that a used part only?
I believe you can buy the connectors at NAPA. Otherwise, Mopar performance or used.
Another way to go is to scare up a Mopar breakerless distributor (I guess you have) and use an HEI module. I just use the 4 pin module. One of the members on here sells "helper kits" to get HEI running. Even without an improved coil, these deliver more spark, as a ballast is not needed.
Another way to go is to scare up a Mopar breakerless distributor (I guess you have) and use an HEI module. I just use the 4 pin module. One of the members on here sells "helper kits" to get HEI running. Even without an improved coil, these deliver more spark, as a ballast is not needed.
I've been running one for the last couple of years
"Emergency" ignition. I originally built this for firing up a couple of junk engines. Then realized I could throw it in the trunk and have "a spare."
"Emergency" ignition. I originally built this for firing up a couple of junk engines. Then realized I could throw it in the trunk and have "a spare."
grassy
Well-Known Member
...I got rid of my ballast....
I've been running one for the last couple of years
"Emergency" ignition. I originally built this for firing up a couple of junk engines. Then realized I could throw it in the trunk and have "a spare."
That's a neat setup...
That's probably a cheaper alternative anyway, and I can bypass the ballast resistor. Thanks again!
BillGrissom
Well-Known Member
Since your wiring harness is for points, an HEI module would be simpler wiring than a Mopar box since no ballast needed. If you had a SB or BB, you can buy a whole new distributor w/ HEI, but a slant requires custom fab. I put the HEI module on the inner fender above the distributor in my slant. One guy sold a plate to mount one under the distributor, but that is a grub zone. I used the 8-pin module since better connectors and allows later spark control. Many posts here. Cheap at junkyard.
A little advice, If u go the hei route, I'd go to the slant six .org and wire it in with the relays as they show there. Before I changed my god daughters volare back to the mopar ignition, it burned up two gm ecu's, which I attribute to not adding the relays into the complete circuit. Ran like a champ for a few months each time and then the ecu's dumped their oil and then ran like crap.
My buddy Paul did the conversion on his and even makes a heat sink plate which mounts to the alternator bracket. He swears by it, and his slant performs better than any other I've driven.
My buddy Paul did the conversion on his and even makes a heat sink plate which mounts to the alternator bracket. He swears by it, and his slant performs better than any other I've driven.
It sounds like HEI is the way to go. All I'll really need is the module in this case, and a bunch of connectors. I think I already have a scrap sheet of aluminum to make a heat sink. I've got an electronic distributor...sounds like a plan...
BillGrissom
Well-Known Member
For HEI, get an 8-pin module w/ GN coil and cable to it from a 85-95 GM V-8 truck. Also snip the connector & wires to the GM pickup. Many photos on-line. Then, all you need is a Mopar dbl bullet connector to connect to your e-distributor. Don't use an appliance type dbl bullet (pins too short).
-
Similar threads
